Transportation advice from Naples to Sorrento

Circumvesuviana commuter train. The station is underground under the central station you will arrive on. Look for signs to the Circumvesuviana. Get tickets and go downstairs to catch one to Sorrento.
Check the timetable below. Circumvesuviana is part of the EAV (ente autonomo Volturno) transit agency.
http://www.eavcampania.it/web/en

Steve,

As Roberto mentioned, the Circumvesuviana is the quickest and cheapest option. The trip to Sorrento is about an hour as I recall. Note that they have several lines so be sure to board the correct train. Also, BE SURE to watch your luggage while in the train.

You will likely be standing in the door vestibule area of the Circumvesuviana, with a fund-raising accordion band nearby. So your luggage will be close by - it won't fit in the area of the car with seats. When the train gets to Sorrento (end of that particular train line), it may take 5-8 minutes for everyone to get through the exit gates and down the steps (or one elevator) to the street. So don't worry if you feel like you're exiting a football stadium after a close game. Note the bus stops in front of the station because you may be using them later in the week-for, say, Positano. If you take a cab to the hotel, try for one with the town cab logo on the door, and ask for an estimated price to your hotel. We were overcharged by a no-meter cab with a light on the roof (not "robbed", just overcharged.)

The Naples station rest rooms (1 euro per person) are just as far the opposite way from the escalator down to the concourse as the Circumvesuviana is from the escalators. So you might pool your bags for watching and take turns walking to the bathrooms if you need them before the 1:10 ride to Sorrento. Watch for orange and lemon groves as you approach Sorrento, and the view down the valley to the bay, near the Meta stop.

Edit: We splurged on a car service from Sorrento back to the Naples RR station ( ... for Rome). The hotel booked their local provider for 95 Euros on the hotel bill. Interestingly, when I offered to book our "Amalfi drive" driver from the same firm, directly, after our Amalfi drive, he honorably declined to consider such a booking. Even though it was a holiday, road traffic was substantial, if not horrific. It wasn't much faster than the Circumvesuviana, but much pleasanter.

Steve, you specifically asked the cost of a taxi from Naples to Sorrento. A month ago, a taxi driver in Naples showed me the printed rate card for this, and yes, it was 100 euros, door to door. That would be the quickest way, non-stop, and reducing any time of finding and waiting for the right train, getting tickets, dealing with baggage, and getting to your hotel once in Sorrento. You don't say if your hotel in Sorrento is in town, thus maybe walking distance from the station, or if you would need a taxi on that end. If you do end up taking a taxi, be sure to agree on the total price for you and your bags before you get in. Even though the Naples-to-Sorrento taxi was quite an extravagance for me, as just one person, I did it anyway (I was staying a few miles outside of Sorrento) and it certainly eliminated any hassle of the trip, and allowed me to enjoy a full morning and lunch in Naples, and then a full late afternoon, evening and dinner in a Sorrento. Back home, I don't miss the 100 euros, but I would have missed the experiences of the leisurely day in Naples and Sorrento.

A Sorrrento based private driver is usually about 20 to 30 euro cheaper than a official taxi from Naples airport/station. He will meet you at Arrivals and help with luggage etc. IME the drivers usually speak fairly good English which has not been the case when using official taxis. Not a problem for us but you may wish to take it into consideration.

This company is popular and there are others at about the same price

http://www.transferelax.com/our-services.html

NB if you do decide to take an official taxi you MUST agree the fixed price fare before you get into the car and the driver must not turn on his meter. This is the official advice from the taxi licence authorities.

Looks like you're covered. Buon viaggio.

This is absolutely the greatest resource ever! Thanks everyone for the input! we leave tomorrow, I will reciprocate with reviews and recommendations for hotels and food!